Subcellular distribution of farnesyl protein transferase in rat liver

Farnesyl protein transferase (FPT) activity was measured in rat liver subcellular fractions by using an unspecific acceptor for the farnesyl groups. The highest specific activity was found in mitochondria and it exceeded that of the microsomes three-fold. Considerably lower specific activities were found in the nuclei and cytosol. Further subfractionation revealed that the mitochondrial FPT activity is located in the matrix. The beta-subunit of the mitochondrial enzyme has an apparent molecular mass of 46 kDa, which is similar to its cytosolic counterpart. The results suggest that protein farnesylation can take place in a number of subcellular organelles.